Researchers make bottles easier to open by making them parallelograms

Glass is losing popularity to plastic almost across the board. Sometimes this is purely an issue of cost, as cash-strapped companies try to cut corners wherever they can — it’s partly due to the steady advance of materials science giving us better plastics. Still, sometimes the issue is that plastics just work better than their more traditional alternatives, and one of the best examples is the threading on jars and bottles: in many cases, plastic-on-plastic allows the lid come off much more easily than glass on aluminum. If glass could be made easier to open, perhaps it could make a bit of a comeback outside of the premium-level food brands that now comprise most of its users. A new patent granted to a team of Japanese researchers sets out to do just that — with simple geometry.

We’ve all had to resort to smacking jars with cutlery or passing them around a table in a test of He-Man strength — though as we all also know, the credit truly belongs to the person before the person who opens a jar, since they obviously loosened it up. Regardless, one of the biggest issues in lid stickiness is shape; a shirt or kitchen towel can help provide some extra grip, but a smooth circular lid is still hard to hold onto against great force. What shape would allow the strongest natural human grip, and thus the easiest-to-open lids? The parallelogram.

The parallelogram design (left) proved the best for natural grip strength.

The researchers performed an ingenious series of tests with various jar shapes, from a self-reported level of difficulty to electromyographs measuring muscle use in the hands. One test saw the researchers using clay to keep a record of grip strength and the points receiving the most physical force. They used participants from their 20s to their 80s, which makes sense since glass jars present the biggest problems to elderly people. Amusingly, the team predicts that jam and a form of soy sauce preserve called tsukudani will be the earliest adopters — they know what their geriatric audience likes.

The team hopes this patent will spread throughout the jar-making world, and perhaps even bring a stronger and potentially more sanitary storage material back into the budget isle of your local supermarket.